Electroplated iron-phosphorus films generally have a higher hardness than electroplated iron films. Accordingly, it has been known to plate aluminum alloy pistons, cylinders, etc. with an iron phosphorus alloy to improve the abrasion resistance and galling resistance of these articles. Iron-phosphorus electroplating baths which have been known in the prior art generally comprise a ferrous ion, a hypophosphorus acid or a hypophosphite salt, and may contain other optional materials such as boric acid, aluminum chloride, ammonium chloride, complexing agents, etc. One of the difficulties associated with many of the iron-phosphorus electroplating baths described in the prior art is cracking of the deposited alloy and loss of adhesion to the substrate. The presence of cracks in the alloy results in reduced hardness and also tends to reduce the toughness of the alloy coated work piece. Accordingly, it would be desirable to develop an iron phosphorus electroplating bath which would produce alloy deposits which exhibit little or no cracking or loss of adhesion on annealing.